text: a=int(input())
  S=input()
  k = 0
  s = ""
  for i in range(0,len(S),a):
      if (i // a)% 2 == 0 :
          s += S[i:i+a]
      else:
          s+=S[i+a-1:i-1:-1]
  
  for i in range(0,a):
      for j in range(i,len(s),a):
          print(end=s[j])
  